1. Field of the Invention
The present invention relates to a catalyst for production of bisphenols, and to a method for producing bisphenols with the catalyst, and more precisely, it relates to a catalyst of high activity and good heavy substance resistance and alcohol resistance for production of bisphenols, and to a method for producing bisphenols with the catalyst.
2. Description of the Related Art
It is known that bisphenol A [2,2-bis(4-hydroxyphenyl)propane] is an important compound for the starting material for engineering plastics such as polycarbonate resins and polyarylate resins and also for epoxy resins, and the demand for it is much increasing these days. It is publicly known that bisphenols such as bisphenol A are produced by reacting phenols and ketones in the presence of a catalyst, acid-type cation-exchange resin. For it, it is also known to modify the catalyst, acid-type cation-exchange resin with a nitrogen-containing sulfur compound for increasing the catalyst activity (e.g., JP-A 57-35533, 6-340563, 10-251179).
However, the modification with a nitrogen-containing sulfur compound has some drawbacks in that  less than 1 greater than  if the degree of modification with it is high, the sulfonic acid points of the ion-exchange resin are damaged and the resin activity is thereby lowered and  less than 2 greater than  if the degree of modification is high, heavy substances (side products in reaction) readily adhere to the pores of the ion-exchange resin to promote the resin degradation, but  less than 3 greater than  if the degree of modification is low, alcohol in the starting material ketone promotes the resin degradation.
The present invention has been made in consideration of the viewpoint mentioned above, and it is to provide a catalyst of high activity and heavy substance resistance and alcohol resistance for production of bisphenols, and to provide a method for producing bisphenols with the catalyst.
We, the present inventors have assiduously studied and, as a result, have found that, when specific nitrogen-containing sulfur compounds are combined for the modifier for the catalyst, ion-exchange resin, then the object of the invention mentioned above can be effectively attained. On the basis of this finding, we have completed the present invention.
Specifically, the invention is.summarized as follows:
1. A catalyst for production of bisphenols, which is a sulfonic acid-type cation-exchange resin modified with (a) a pyridinealkanethiol and (b) an aminoalkanethiol and/or a thiazolidine.
2. The catalyst for production of bisphenols of above 1, in which from 8 to 55% of the sulfonic acid group is modified.
3. The catalyst for production of bisphenols of above 1 or 2, in which from 3 to 35% of the sulfonic acid group is modified with the component (a).
4. The catalyst for production of bisphenols of any of above 1 to 3, which is for producing bisphenol A.
5. A method for producing bisphenols, which comprises reacting a phenol and a ketone in the presence of the catalyst of any of above 1 to 4.
6. The method for producing bisphenols of above 5, wherein the phenol is unsubstituted phenol, the ketone is acetone and the bisphenol is bisphenol A.
7. The method for producing bisphenols of above 6, wherein the methanol content of acetone is at most 3,000 ppm.